Asymmetric Total Synthesis of (−)-Amphidinolide V through Effective Combinations of Catalytic Transformations
作者:Ivan Volchkov、Daesung Lee
DOI:10.1021/ja401717b
日期:2013.4.10
The synthesis features a base-catalyzed alkynyl silane alcoholysis/ring-closing enyne metathesis sequence for facile construction of a 1,3-diene motif. A diene RCM followed by a ring-contractive allylic transposition of cyclic silyl ethers was incorporated for the stereoselective installation of a functionalized 1,5-diene subunit. An efficient proline-mediated direct cross-aldol condensation of two
完成了 (-)-amphidinolide V 的不对称全合成。该合成具有碱催化的炔基硅烷醇解/闭环烯炔复分解序列,可轻松构建 1,3-二烯基序。引入二烯 RCM,然后是环状甲硅烷基醚的缩环烯丙基转座,用于立体选择性安装功能化的 1,5-二烯亚单元。两种高级醛中间体的高效脯氨酸介导的直接交叉羟醛缩合被用于构建关键的 α,β-不饱和环氧醛。这种全合成证明了金属催化转化在复杂分子合成中的威力。
Meerwein's Reagent Mediated, Significantly Enhanced Nucleophilic Fluorination on Alkoxysilanes
作者:Toyoshi Shimada、Yogesh Jorapur
DOI:10.1055/s-0031-1290757
日期:2012.4
We developed a new facile method to fluorosilanes from alkoxysilanes using Meerwein’s reagent. Our protocol afforded fluorosilanes in excellent yields in various organic solvents including acetonitrile under mild reaction conditions at room temperature. We also proposed a reaction mechanism with the probable silyloxonium intermediates.
An Efficient Method for the Synthesis of Symmetrical Disiloxanes from Alkoxysilanes Using Meerwein's Reagent
作者:Toyoshi Shimada、Yogesh Jorapur
DOI:10.1055/s-0031-1290668
日期:2012.7
report here a new and efficient route to symmetrical disiloxanes from their corresponding alkoxysilanes using Meerwein’s reagent as mediator and potassium carbonate as additive under mild reaction conditions in acetonitrile. Our methodology is very simple, economic, and high yielding. We have also proposed a reaction mechanism with the plausible silyloxonium intermediates. We report here a new and efficient
Inter- and intramolecular carbonylative coupling reactions proceed between alkynes possessing diphenylallylsilyl group mediated by dicobalt carbonyl complex under argon atmosphere. This coupling reaction directly provides various mono- and bicyclic cyclopentadienones in high yields. (C) 2000 Elsevier Science Ltd. All rights reserved.
Gold-Catalyzed Intramolecular Allylation of Silyl Alkynes Induced by Silane Alcoholysis
作者:Sangho Park、Daesung Lee
DOI:10.1021/ja062560p
日期:2006.8.1
The activation of alkynyl allyl silanes with a cationic gold catalyst in the presence of alcohols provides vinyl silanes that contain the allyl group at the beta-position and the alkoxysilyl group in cis-orientation. The bond reorganization process is most consistent with the involvement of a carbocationic intermediate, which undergoes a nucleophilic attack by an alcohol selectively at the silicon center. The cis-vinyl silyl ether products can be further elaborated by ring-closing and cross metathesis to form more substituted 1,4-dienyl silanes.